In WO 2009/150165 A1, a filter unit for filtering gaseous fluids is described comprising a filter insert part with a filter medium and a sealing element, said element being clamped between sealing struts on parts of the filter housing. The filter element assumes the shape of a rectangle and is comprised of a folded filter paper which is circumferentially enclosed at the edge portion by the sealing element. In the assembled state, a sealing section of the sealing element projects into a receiving space which is formed on one of the housing parts. A second housing part covers the sealing element and acts on the sealing section transversely to the mounting direction of the filter insert part.
The sealing element extending circumferentially around the filter element is typically molded or foamed, for which tundishes are provided into which the sealing material is introduced in the non-cured state, whereupon the sealing element is inserted. After curing, the sealing material is fixedly connected to the edge portion of the filter element. In the tundish, in which the non-cured sealing material is introduced, vent openings are incorporated through which the sealing material can escape. After curing, drip-shaped elevations of sealing material are situated on the outer side of the sealing element in the region of the vent openings which must be cut off to obtain a smooth sealing surface on the sealing element.